mysql查询语句更新字段

(select t2.customerid as khid, t4.realname,t2.oldownerbyid as jiuid,t2.createtime as gxsj
FROM crm_customer_handover as t2
left join crm_customer as t3
on t2.customerid = t3.id
left join sys_user as t4
on t2.oldownerbyid=t4.id
) c
set t1.ishandover ='1',t1.oldownerbyid=c.jiuid,t1.oldownerbyname=c.realname,t1.handovertime=c.gxsj
WHERE
t1.id = c.khid